1. Field of the Invention
The present invention relates to an on-vehicle navigation apparatus which displays navigation information, such as the distance and direction from the present location of a vehicle to a destination.
2. Description of the Related Art
There is an on-vehicle navigation apparatus known which has map information including road data acquired by digitization of individual points on roads or streets on a map stored in a storage medium such as a CD-ROM, reads from the storage medium a group of map data of a certain area containing the present location of a vehicle, while tracking the present location, and shows the data as a map around the present vehicle location on a display as well as automatically displays the present vehicle location on the map. This the of prior art is disclosed in, for example, Japanese Provisional Patent Publication No. 63-12096.
This on-vehicle navigation apparatus computes the direction and distance from the present location to the destination to be reached, on the basis of the outputs of sensors such as a direction sensor and distance sensor to display the information on a display. The destination data is input by a user such as the driver operating keys to be stored as destination coordinate data in a memory. As long as this destination coordinate data is present in the memory, the direction and distance from the present location to the destination can be computed in accordance with the destination coordinate data and displayed on the display. Therefore, when the vehicle starts traveling toward a new destination after arriving at the destination indicated by the data stored in the memory, unless the destination coordinate data was erased from the memory, the direction and distance to the previous destination would be computed. This requires a troublesome operation for the user to perform a key operation to erase the destination coordinate data from the memory. As a solution to this problem, there has been proposed an apparatus designed such that when the distance from the present location to the destination becomes equal to or smaller than a predetermined value while the vehicle is running, the destination coordinate data will automatically be erased from the memory. This prior art apparatus will however give rise to new shortcomings such that the destination coordinate data may not be erased even when the vehicle has arrived at the destination if the destination is a wide parking area, and that the destination coordinate data may be erased, stopping the display of the direction and distance, even when the vehicle has not yet arrived at the destination if the destination is a building-concentrated area.